Alliteration is defined in Encyclopaedia Britannica as “the repetition of consonant sounds at the beginning of words or stressed syllables. [ . . . ]  Alliteration is found in many common phrases, such as “pretty as a picture” and “dead as a doornail,” and is a common poetic device in almost all languages.” (“Alliteration”).

As Merriam-Webster cites: “In alliteration, consonant sounds in two or more neighboring words or syllables are repeated. The repeated sounds are usually the first, or initial, sounds—as in "seven sisters"—but repetition of sounds in non-initial stressed, or accented, syllables is also common: "appear and report." Alliteration is a common feature in poetry, but it is also found in songs and raps and speeches and other kinds of writing, as well as in frequently used phrases . . .” (“Alliteration Definition & Meaning.”).